Comprehensive analysis of combat casualty outcomes in U.S. servicemembers from the beginning of World War II to the end of Operation Enduring Freedom

Jeremy W Cannon, Daniel N Holena, Zhi Geng, Ian J Stewart, Yanlan Huang, Wei Yang, Emily R Mayhew, Shawn C Nessen, Kirby R Gross, C William Schwab

J Trauma Acute Care Surg. 2020 Aug;89(2S Suppl 2):S8-S15

Advances in combat casualty care have improved combat survivability over the past two decades. However, these outcomes remain incompletely framed in the broader context of combat casualty outcomes over the past eighty years. We hypothesized that starting with World War II, combat survival worsened at the beginning of each new conflict but then improved over time. To evaluate long-term trends in combat casualty outcomes, monthly combat injuries and deaths during World War II, the Korean conflict, the Vietnam conflict, Operation Iraqi Freedom (OIF), and Operation Enduring Freedom (OEF) were collated. From these numbers, we calculated the monthly case fatality rate (CFR), the killed in action rate (%KIA), and the died of wounds rate (%DOW). We analyzed these metrics for significant trends during and between each conflict using linear and Loess regression. We then simulated alternate outcome scenarios by eliminating outcome variability. In this comprehensive analysis, CFR decreased over the study period in parallel with a decrease in %KIA. When examining individual conflicts, however, several unfavorable trends emerged including a spike in all fatality measures at the end of Vietnam and a rise in %DOW over the course of Korea and OIF. In comparing CFR at the beginning of each conflict to the best CFR from the prior conflict, high mortality outliers occurred in every conflict after a period of relative peace, and a clear "peacetime effect" occurred in both World War II and Vietnam. Eliminating these negative trends and the attendant preventable deaths would have reduced combat fatalities over the course of eighty years by 107,256 (39.7%). In summary, although combat mortality rates have generally improved since World War II, closer examination indicates several unfavorable trends both during and between conflicts. Identifying factors behind these trends will reveal further opportunities to improve combat casualty outcomes in the future.

LEVEL OF EVIDENCE: III, Epidemiological.